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Several Environmental Factors Influence Process

Carnivorans are the large mammalian order including dogs, cats
and bears. While they vary greatly from one species to another,
their skulls tend to take the form of a few shapes. Scientists have
long attributed this pattern to a shared diet.

The new study, however, demonstrates that there is far more
variability in environmental influences of skull function and shape
in carnivorans than has been understood.

“One of the main findings from this paper is that the
anatomical variations we observed across species are related as
intimately to diet as they are to several environmental
factors,” Tseng says.

“These factors don't necessarily have to do with feeding
behavior or preference, but still can significantly influence how
different skulls function as food processing tools,” he
adds.

Digital, Biomechanical Models of Skulls Utilized

Together with co-author John J. Flynn, PhD, the Frick Curator of
Fossil Mammals in the American Museum of Natural History’s
Division of Paleontology, Tseng used data from more than 50 living
species to develop sophisticated structural and biomechanical
models of a broad range of skulls from carnivorans with every
imaginable type of diet.

The pair used the models to see how skull shape and size are
related to and influenced by the environments of each species.

They found that, for example, sexual maturity and
precipitation-related arboreality (how much rain falls in a habitat
influences what species eat and how they interact with their
environment) can generate structure-function relationships in the
skulls of carnivorans that correlate with “masticatory
performance.”

Studying the Relationships Between Structure, Function

“This is a common theme between my different model
organisms (carnivorans vs. humans),” explains Tseng, research
associate at the museum. “The relationships between structure
and function allow us to make predictions about how well parts of
our body work given their anatomy, but factors influencing those
anatomical variations do not necessarily have to be directly
related to the functions those variations affect.”

“Understanding the proximal mechanisms of a structural
system — be it a bone-crushing carnivore skull or a patient
suffering from temporomandibular joint pain — is not the same
as understanding the systemic pathways that underlie an
evolutionarily adapted system or development of a pathological
condition.”

The National Science Foundation and the Frick Fund of the
American Museum of Natural History funded the work.